Coronary microvascular disease, also known as small vessel disease, is a condition in which the small arteries in the heart become narrow. Typically, the walls of the small arteries are damaged or diseased. Coronary microvascular disease affects the vessels differently from traditional coronary artery disease. Coronary artery disease is an obstruction of blood flow through the coronary artery due to plaque accumulation and blood clots that form as a result of the accumulated plaque. However, the accumulation of plaque and resultant blockages are not always present in coronary microvasculature disease. Instead, coronary microvasculature disease is caused by an adverse constriction/relaxation of the small blood vessels. This adverse constriction/relation is believed to be caused by changes in the arterial cells and the surrounding muscle tissues. Coronary microvascular disease is especially problematic in women, who are more likely to experience the disease relative to men.
Diagnosing coronary microvascular disease has been a challenge. Conventional methods (such as angiography, stress test, and cardiac MRI stress test, etc.) are designed to detect blockages in the arteries. These tests are unable to consistently diagnose coronary microvascular disease because the small diseased vessels are often unrestricted by plaque, and thus are not visible on angiograms and MRI scans. Accordingly, women and other susceptible groups, such as diabetics, experiencing unexplainable fatigue, chest pain, or overall malaise associated with heart disease may test negative for heart disease.